Chloroplast Small Heat Shock Protein CsHSP24.6 of Tea Plants Positively Regulates Heat, Light, and Salt Stress Tolerance

Small heat shock proteins (sHSPs) function as molecular chaperones, which play crucial roles in plant growth, development, and stress response. However, the function of the sHSP gene in the tea plant ( Camellia sinensis L.) has not been extensively investigated. In total, 54 C. Sinensis small heat shock proteins (CssHSPs) in the tea plant genome were screened. Phylogenetic analysis revealed that CssHSPs in the same group have similar conserved domains and motifs; conversely, significant structural differences exist in the different groups. Most CssHSP genes had tissue-specific expression. They also responded to one or more abiotic or biotic stresses, CsHSP24.6 was selected for functional analysis. The results demonstrated that the expression of CsHSP24.6 increased under abiotic stresses such as temperature, light intensity, and NaCl. In addition, under high temperature and high light intensity treatments, CsHSP24.6 and its target gene CspTAC5 interacted to enhance the heat and light resistances of the plant. CsHSP24.6 facilitates resistance to abiotic stresses in tea plants. These results further support that CsHSP24.6 plays an essential role in maintaining plant growth and development under abiotic stress.